SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '991a3ba5b0399c69960a206b9351bd086a7180b9ae1904cd4ce22dee13336171' 
  AND token = 'WYWC8IZECG8b4kx35zKmlyfZirNh0UMXxu0aABCM+Hk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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