SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ba39ccfeefb6ae22edd07c43e64730362375444542efebcce1d08799a164bb09' 
  AND token = 'sVj2YHPglyc7SuhB5ksUXvXgDohFtCpPbVq0/2uJ1E8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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