SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83debee56acd87e061be2bca3f35269049ef4a187e7bbc1099987ec8fef95f34' 
  AND token = '+LKI7DVw+0hVJlFupxUmxnqySUSYwx9ryPghl+raBbY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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