SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38bb9136edbdaefec2ecaffc8656c85605f75d451babe5f0d56ec8b1405c75df' 
  AND token = '3fiN6eoV4bYMFwpNBNhx8xAeqgTJiyxCXg2UKwqMaIk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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