SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2c52bd63a742fc05cd8337182a8f35588021d8d7aa8728657df204b47bba491' 
  AND token = 'bkX9E0LbMjoN7ULw3Od1NEhwLFRKyZJWgGiIr+tWO30=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}