SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8544b579241e8e010de732255237d694241cd2278f477ed1f98668496bd0f67' 
  AND token = 'Oi6oFZDvl/KelYwYIJGJyEN9o29VMTCDQPFyT6gL6Gg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00011

JSON explain

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