SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '21fe5e796b4fceed69599da8096a7bfbabba6b977f2254ab791da1adbf278234' 
  AND token = 'FzxiKxLSV652x4CXe5vt+RhOrbAlAmh40p/Wta5IxWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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