SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b99c55471ffc3c0670cb683255d3888511ac410abffb67cae66297d30656f2d3' 
  AND token = 'zsHP15EFM+eQWmrI/lpniL9pnIDXG2afQdT9ze2+658=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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