SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ad294271829521c40e92440b5f06e56a71cd4514eac4eedb12582a2fa127da0' 
  AND token = 'QVS679mlkSDKcKJslhKQdtaBM4Hke71OxTAy7KA9b9c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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