SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e29829b19d50892d6d99ef52d32c7fd5874322fd96381df8afbc5508acab83d9' 
  AND token = 'Rel+x5QYNbEWryPFWeNCnr0a2Moxd43Bx0JEYgUAq58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}