SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fff84c54883493fe364bf69d785d2ffd1c94cb24c0247c878c9b86447ed42234' 
  AND token = 'gXmh4zL1SFOWI3stSHHLBGkc8Rw+RmRBiAgwoh4SeZg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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