SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70971d6a79332026a1dec36f65fdaa4716094c81718a68bc1463b2621845ee59' 
  AND token = 'sqfpizG+3RyFARzNjhUq/ZnQ3uus6r76c37NPhl6Csg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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