SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fc4ee86b481626744123ac1690a39105cc79b716a8d5201f09a34fb94c85f9f' 
  AND token = '/sG3LVyn/GWaiQ8QYPChQ1hnwD+2qwKb6PIHMo9yjWA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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