SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68f161ec7f6ca06fc650bc4cf9a8836b986a6042a2142c3bdde94c81543c246b' 
  AND token = 'HZUg5SZzY3XJWvMsTS906b42ybeTnCHV9XAdq5Mtkq4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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