SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '72b33a048ace9288152c0274b579c298be5bc6ee2d73a42082e616192662e7e8' 
  AND token = '0iw21JBAmHd31KhD7ywrHwuaLVmMNTxeKzUsPealsOs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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