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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9c55797e017b4ba79a87d14262e07848c07c77de97cf7b688934ac5027aca60' 
  AND token = 'k61+B0arUiO7g2QOQOX427ozABldTo14qsOIpj4Tw2o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}