SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7857960d5829abedb8d546d6cff6718b8522b40987d443cce3f706a417572631' 
  AND token = 'ms+yojaW6ky1m2Ed9XIpefDBzZqB48AFWVyChVczlbg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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