SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '620e116ca65bd075d8a927769701284beec3f71746dd12f9f46897bc66799e92' 
  AND token = 'ylswAjO20LNJja0yUgSMWJ5BWafFWYU7RuM47ujvRCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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