SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5b9053d3b0bda0816e3a8b64e2b5759aaf6727cebce4b172dd860cc906c199b' 
  AND token = '98FkpEx02Op4iH4blRNpwbzMmpHbTif/6NdVQ1qQLTw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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