SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '052a2dcb7fc7d0ccd0aec7f041f37be444bacc79dbbb4a480a52755486d6235d' 
  AND token = 'uz2j+zNTSiBw4KfoWZIS8+/g6kQFFLNsXNxisSnNu5E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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