SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6758a63a2220b48b3992e0eeaeed7073c9291dec897eeaa65d14ad8c1bc487a' 
  AND token = 'RqCoOYVdWBltphmBjZtGHr+7sPlqH355YEtAkcUCw/4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00083

JSON explain

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