SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e86abc40e268824c9501e47821000ea5856107beb384698a493d01bd9240a36' 
  AND token = 'dVx3tnQnzpuixH/eB4g9FkJObX7FUqLyzldW26Lj/FU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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