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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81c061f80e5d163427c3d87ab0c423667e2d078d4f4aed254cbab86bad3d8d6c' 
  AND token = 'aL4rXm8jxqAE5q7+bdDI786z9EqLtdsCmjKzE0FlNfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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