SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12348d8c145036400b518a28a763d99fa4a28aac5505697ab86102367adea99b' 
  AND token = '0vF82P5mSCj8usBCBeaFJKh179fnlvXpcLZ61Di+qhU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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