SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae578024392d72b4fe4d112df892848a375089f1722f0ea9b5b725b16a253726' 
  AND token = 'pPxNtVvXPgGrS0I/e+fLiWkfZEiWZCd1NtOAB2nLAQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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