SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'cf4b6ff5646f5c25e9f3d2c30f86818683c6f0342affda1370b92e397cf0d373' 
  AND token = '81rzVf69ag8UPStfkwSUviFfita5fNspH11gl0kgCRA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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