SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd8511e78b8b6014b515a2c1d92dc503121c1eb65cd3541ee3e767c360253043' 
  AND token = 'PaNyReWZRfjgeq47Xdfh2pIcYxzCFhsc0p1jygpHl8w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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