SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50bc7b7272034e3c6ffd483111651e3851571371cb23907f22b133a001693a61' 
  AND token = 'UyxS6LbdPY8wBjN14X2xweNj6yIcXEcb1OZgxUKbavo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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