SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '806ac6ef8c25a54688a88538ab11d2d315ab6d21fc3248fa220a66d6e254bfb0' 
  AND token = 'AMmJcUMeq4RDH23PoRbXpbxVBa/9OUFpmYrT/oW2yn8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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