SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4aed7bd6039701441a7123372585e9a2818c689187195db738a5d3d3423fc865' 
  AND token = 'ROiU7u4/GpiDXVLJoGvnpMnUTZin/BSSuhf9sG0kBrY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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