SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '626405ec7a1e141d68a140624838d9c0f3ed1307990016eb0f4a3d6686c17ddf' 
  AND token = 'gKYjWuQ137Ods8eEPOTR3lUwsVQAhHq2Ydlbj+MuGxg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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