SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20b964a7e0bbc53a58a41220c3848158578b3d8a2d9634c8f60e918dc1214249' 
  AND token = '4qhe+hIPJuk6fc9jFvFiWlMp6fJ6e7FfgqKT58gwdHw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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