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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '49c766628d89c1e9e573e6bfc390a8fb9a00e498e823e74426dd0e41475ffaa6' 
  AND token = 'Z4OvbmfXSgm9CbxRIGRxGK3M6Hiu8/e6Nvh0agUeqLw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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