SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '735423a25675e11d3fefc452d6ff84f907057372415f076c42c7e997df614ec2' 
  AND token = 'JP8Ml81ay2zhJh4GFC1TCiMfkG9AzTr154qQ3DEnJOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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