SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3df3f07913823de2f5efa10284b14e563c11d03e4b4a3d910aa7fc78b3811b88' 
  AND token = 'kx7YK+rcZ0AP7BnPXZzENMKwng/vNTySDLezzzAupSc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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