SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '790052a258bb64cfc9f023c4241a2378c88632672360c5db2353ad82dfb93496' 
  AND token = 'Zh4mfxPsZw8ETtA9vbVQSOSIfakM8kf5ymzXhNyCFh0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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