SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40f838ddb0aa1ec204aeca5f58b337abeb566b3dd69b6aa195dcba1806c139a2' 
  AND token = 'k/IhHzFAlWxxrXY8h8VseCBgAAs3uJMGERzyYpujw+Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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