SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd66e3c7cbb6e7744501f5346fcb8b090c99cb15268495823ff68dd36c03a7773' 
  AND token = '2FzxGwMFoPCcssQzhn27ppk8a3CIcSuuXBSRq2KjS5w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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