SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '287155234ba4cef4578c897df3b716ffdb86a40c71519d26d69fff60b0b93b95' 
  AND token = 'FueqFgIPDWxd0L2fjRdXWzYpcAJhk2p0IC+jBwqv3Go=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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