SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d520bceceb63a730a735d58b18b4a1e0abf31084f83f74e53746c67ad2b94b1' 
  AND token = 'QatyWgorkefifmJCoygmpzN1KzrukgryRrNsslTowWg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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