SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6f5c1a87343a43d208bf447c0394916a8b1dabd9f0420bb6a2e8cc59040785c' 
  AND token = 'iDuGOgYBt3r9VRkJjcX6N9qQlTRTusqH/xhoV5fbBRc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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