SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92f41bfc643246ee07c1d4c1f0b975755e804155b41272184e84af7a48dde098' 
  AND token = '+vi7D+uEgryTtZBL9ClFoMq9d6TvYGxIfKG3QxOtHaw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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