SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a7bf30a27841d463139f865c6ff723274e4549c0aac9221a9e506b4880458fa' 
  AND token = 'UZJfGtV+oXRh+Jm0NkCAPus3TgnlJavhtqegYqC0SOE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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