SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83ba5fa05dbee1d76cbf86aa4809becdc72b15bc6430699f46e21da945788c50' 
  AND token = 'zix28CKq+bCHJPCwJsjJKCZfuKnrRUA5VZAB67WJKSc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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