SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b7fe33a135513959f8daadd1e5c2f828eb2616862484c4620d2c45541c0a5c2' 
  AND token = '+ePXPybiYtvJ4zvhhZ5cmMtWiiwrVHpdwDNp9lMgJjs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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