SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0891cd592c7ddaa372e14e1b4916cd2afe6e12914d3c754213263fb4b827abce' 
  AND token = 'yta0MKvOxVugqfCdwQtISmS3KxQWVbwtyjhudcKr7MI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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