SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '774e194d702b3bf397fcb1a47dfa426607521c221fd1022ce802526018918d0f' 
  AND token = '3GvuqkAmQdl5CyjXL8/UasvyQSE9YjwrBwQNwzk3z6g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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