SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b221c8dc89c50faac998603bfcf9ecdadef50abda003fce888369f70d93201b2' 
  AND token = 'ZSG3XZCrSKEAqNMOIigVGcT/QkDjNThAWXIwslknYUw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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