SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b7c3c3815f70487b5220436ed57e8964eb4868272f97c1793588e30dae049ed' 
  AND token = 'zCZUl36OVsYvgIKWTeetm+z8raQuWvWPyhXXaImdG2k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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