SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c30a3b14442de8492c695ad776dafd27c38f29b0fb74ef8c0387f3a06c72658' 
  AND token = 'CQsowx55oN2+oUE5mWmMofKTC9927yifP4whiZTbMeI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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