SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab7c3a4c7d56318b79931bb68459857e9a8c4c7423af08f3d4e21aeb02dd1ac7' 
  AND token = 'OMz2hZ64pV1qGnHXJWHZx3uEoRwVZLwKdhqBS8mnpz4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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