SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a99d6772b4fac07e2c38b8d0106e8bb1569598d5553dbb46053be364554c7edd' 
  AND token = 'CtO4qqMhLjRNqrwTRLbpjK9catnBYyUTFrYHbnGR/Vs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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