SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'bd471bdd5ce952873ac4b16a7761537efff084a483f74300fac129499695a28c' 
  AND token = 'ta+du0O+ENip8zUhpRsGgp7ifeuy4hLAKM0LJygmSBA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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