SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '248b798f1ee0acf90fe2b8497eace39fbd893d11ae72ef80768a940b1f099fcf' 
  AND token = 'UgQngxVXaZuY5nczAZr8oCTbsTU6U+DD2INoNM8hV7s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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