SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '940e18ad5016091f97846a80c489abd54fd2a82ded4ac16391e5b76215abc585' 
  AND token = 'vD+GShpnprZbRL7LmjKlLftBXjInjYLnwOMmad4zRSQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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