SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '837c87ca9393a3e2cffe690662ae0af785a090a0eb4e5a09e434a3172128f5c7' 
  AND token = '9UQF2rqufXuymRBoGpD4445zwRfm2BIbJ5eCx0d7Euo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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