SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '93eb0c1fed4d12ed23d05eb2e5f4e508ed493099120719578953162710b73814' 
  AND token = 'zerx6Y9apCjIdltjNHzNVNwHv72VrULadnsvNLTwg4Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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