SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c35147194e572ae75556ebf98ddde22993e91044aebb080e9398a9d853657e9' 
  AND token = '5xofPgXietNezzPbSOszXGHrA71bJhMOrM0AixZv4Uc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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