SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50a2ebdb5d2dcb859dbd3c9e74a68626981332ac3147545c46422c766832d978' 
  AND token = 'optjnTgYMEKI2a5UXP6TsCnwhDS55lZnVuPR7FwF59o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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