SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3283fcd21547863478bff272ebb11c9c8d9e27382ab67979212e739ee8a4e36' 
  AND token = 'nOowVAramMLAzBfxfD+yv9jqT2gd4r9l2NgQ5WqMEsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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