SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0273fe6db5103c26aa0088446213f6452c00d6fc798f0ed540d12aef1068e85' 
  AND token = '/+0Z/kjrKNBaFS05dbijeUyjL4MKTdbrqo8IZaTMRaw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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