SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bacf61dd41b91baeb812e6be0e114a8e735833880147a1d18541c0a2a1ee571' 
  AND token = '1uN5zdZwr4TlLJHaHtXi4vNqGuh6khpAwMlp4zs2WXM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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