SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec1cbf7e736a99bea97ae10be955ed176677bf2bbcb162639e9b234c075d109a' 
  AND token = 'E2RmM2sUmvN321c+8tdCwwJrhTxykgIwkqCVvmJODZA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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