SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3abf9ec91779ff916cbfa5f9a740853f83331da4cc0945fae4a83978bf88fb2' 
  AND token = '45NAjasLkd7xt4mNYQGWSpS0cDqogRAaqfe2da9qDes=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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