SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4d357320b0f09ac329a29da0a63ef2bd155688f751e83990bb452fbd1d7aa4b' 
  AND token = 'ZKQhd3e+XDcnjKlUvHNwFqOX9pp3HWNqmPligEY3lZw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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