SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e2304e940f489d6ec8f420211784b970bd08946c971147a6a18e02b7cb09aea' 
  AND token = 'DTbEmI+lmekkqtcBpdFBvjpxr2KqVZTGY5Us+9XP78o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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