SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df0c168985f0f6b3a591e2f5cfb599a1d8441b50fa3a09fa08da6c89664ffc78' 
  AND token = 'SqFu2rZ7SXpMaRsREwVinATOkz6HAAnPcMatFjN/M9g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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