SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c480a56bcb62e347e128b545dde1b9a796df428753b712cb44986aaad9b7740' 
  AND token = '8KOmBTED+Ls+fopDHGOFonqihX/LqHPbzlwST8CKBow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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