SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '311d69fca250b28ac4168a940531d8a11d83c1e7422ddd085c75082530b53e87' 
  AND token = 'lUNJUQA2jW10HvlgZrrN1NrebrHWSsjp5ODFZo/UyJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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