SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '712c60689dd2932900b042ffacfcaa5dae1d773895915833b4402a98ae82892c' 
  AND token = 'tLHGFRumK28oYzXQirQDm9L/rhzw85RzPrmCPvtdgjo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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