SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9542a70e0f638b07a1133819495166304654c9fb3af83e4fe4138dfa86521658' 
  AND token = '0ysi1mP30WUmscEzLV9cqPZUIEykmKwxAoKRfssRf3Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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