SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4d0cf9e3e7c3a34a58b26c784bdf04de11e2978b7d0d63972d5f99174b6a70d' 
  AND token = 'Yz+TO1WhuUnV+Xy/BMtSTfOX4nkPXeGvkk2Th7dejXQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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