SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfe036cc5450d623be6e33c6e73050887a036f5a92db2f6b1cf46858d1a310af' 
  AND token = '1z/ScxFC0tahw4ZWpOtMBL6GYAu0PIAdZ1pY0yN4wSE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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