SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a2646332135868ea214f3b3578a593d6bc35b939d2ae8107f86bdf339ba73a2b' 
  AND token = 'vK5+SGyTt/AtmQM+K40ucHU4Dzhj0viRW9QBXkZCFOk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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