SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2a9e5f350f3bd2894584cd33bd09ee94aa93138f48b7d96a203684280c98efd' 
  AND token = 'U9pQkaFxQ8kN6+MO2gdcsUY7rMHCodDHYB86Vi1aMjI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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