SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a66d577ce6678350ba46e405f8099f527681006d1b7e904c988813ee951f9fe' 
  AND token = 'KfDdMyv3w55qb8kjMcJaiN+CSSKbOyEK7vvlyJ43+jM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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