SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b9898dabc632c917a783797a02f13488b6c014b1d5e236af193557602146e3f' 
  AND token = 'OeDlSZOTy7lIADeDrHooBR5N4rom0gdcMjl7Uwsmmq8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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