SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e51284688c666aefed6dc1c4b4d103d0cd0ea138c9960f0aa46f309fd34c92b' 
  AND token = 'RlJOKLv0yVNpZTEAtFuQkMi8jisjBjjeTbw6XpJYoD8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00076

JSON explain

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