SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08c1e876412d6fdc7c89a9b9a200014e1abf4062fb41f871414a3439b347157a' 
  AND token = '2E+KwzsnvfaUThZ8HTQvolJzGUM1cyY+UEfaSNcOXak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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