SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '375d3b0ec23953bbd8897f62102a4fd8ae37d142f9c20e956fa1c47eccdaf181' 
  AND token = 'KuhmiGcqjFUGzPeVpqmmop7sXDm4l3nAn9iP+MEFOew=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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