SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e004807a4be2f49fe243174f6ee9504ff599896e2aa30d708b29d987a71df9a' 
  AND token = '6RVH+AwUIN8EnBbSCM38AVz+cigDq7r/tUqpXpkVbhk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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