SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b8aeb69f3dca55fa7870502e2ce3725a3abe27d8efec845d164d723b40ee701' 
  AND token = 'lBx/xDW6N1peS83wkV553HnNzR7pEPzefGPpEuQ8DyQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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