SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be97c3d0f5b2a10b86efb9f0d1b16121e4a981f5b8233f5a218ff06cea7e66d9' 
  AND token = '67jHdGAPULLDqDY8gLCuwG8sbZez3uUKrhFA7cJ7Vxo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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