SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55873e805542db3f5b08d0e0c920321f739a63a88184de7c65c1dd0ebf9da7cb' 
  AND token = 'ZQY1nXf/MGwYwTXYmrzUByCQ+/nPz4pjZQRvsdhQNxM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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