SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b9ac0abf69eb8704f7346c386872d5e5503aec8897fa7ba55d5be3612c96376' 
  AND token = 'YQxpy9hNGCFfLLWj2zP2Ye+nIlTiQ2/IlaetZmZoixc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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