SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '67b41a0a5dbe974016850143898f5b884302c3d5cbc8171890d850ca6fc00678' 
  AND token = 'WHGmYMI2zs3lyTVQwlCbCkfUSCrczzEg32OHmVmvbDs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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