SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2cb334760f45a60889536bc0021baaee77d27ef18e2ca71d6db0c17481e3972' 
  AND token = 'sdrVcBfQPfFh84tF8YrHVAcQarnZ7NqYW5V4a3DfhC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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