SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '312c78ea9d441dc620b170ab066c0fc95c095b11cdc18533042fa49749d1c8b8' 
  AND token = 'cRGgnoU3vmcp0HhSHWloQuIQD4FEJPwGzh0EfkhvAAI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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