SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd267888136027021e1f9bd111022238a91806ec41ab2948223738197f8e31355' 
  AND token = 'ycPvlVrk7BcIyEhi1ISctXk0q5r+ThTAEMru3UU9bBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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