SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8061f009ee20475ff1ed08820ee082d310a7fd1cd62d98c6a50b0a9feceb500' 
  AND token = 'IZNZtyh+6B6cOHZRndM5cgRXzEVW41BLALCHXd7GRWM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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