SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1dfcd87a9e10d69cd89fcc7dd8e6e7005bd4f77827ec32b4a4dc5e972c195510' 
  AND token = 'YT7yFUr1Sd+Fc6RVZj4yF6KlKoUJ3vHPrMgLyc6gLnQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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