SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '537f17f00d009bdb7481dcfb2ff88424ec010eb519382e8d81b119ed77d258dd' 
  AND token = 'KSWVCpe1sgfwq12d8D7H2dCOSQRJUkGE65+Bsp68frI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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