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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6cf4531e71bcda90d159f77adc42900ef4bde0da5f7769bac76259c55afcfce' 
  AND token = 'qcRzUFiMsnSnPmB49ZQjkId/5UYw8+WfhGQfPm2p1j4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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