SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '235659a7c092665b51da55ae45b685900bd1234d56561b909828c2dd4624fc5f' 
  AND token = '3VpAqGnXkx7fJjI1+3gvG2HI0zkHdM5UotsVhye1mC0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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