SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '946a44059740e8097023da16cda61d12d72e762e05e33d74a40f65f0c1fd67fd' 
  AND token = 'IheftHANTdqq2q68S1xHnvhyrEkCEKoENig9dkjddzU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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