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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b9e8a5d7b05889772b21eadcde3f7c80127ccb5b1eb74e2c82ab1ead04e9983d' 
  AND token = 'v79yuORkxQZloRIjkzgnoy4oYWVESsdZt1Esn+3XtE8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}