SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81614f76a324b295025b2202fc5bb887408a689e3a9cc56f0c4d8070aac1fb4e' 
  AND token = '/6DwNmlw/qiF9oBdbY4JXpuRqLfc76DEs/5RGJhsX3A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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