SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f1b39146b8333932512858dafd9264e7bd5f601110c269821a7ab249168ace8' 
  AND token = '8UNxl4f5PHotzVs+dvbcY/Rpdx21JWi6mXytdfjs3Tk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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