SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b71fb40894ac833fc3cb6439e9c143caac9fb5d60f1d1c45636e2437ddf02870' 
  AND token = 'iO2XUVcSulUeXlNvUjp8Qg9XKbBJCVxJTjywF5hPwhk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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