SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49420901d9c9f12e0c2870cd73b24dd7943b10933aeeaf7e879db87331f5eeb5' 
  AND token = 'xq0FtaB4bQ/WDxhFbUNwCcOyuCUmsqu+m3n74DUhs60=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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