SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5ec7d4483cae9b9c9691d39909a90d1031c83cde8182ffc3f9b809e449bf73c' 
  AND token = 'WCguLKkJv+TSbQtwA8IevIWw0AtzzPzxzOmMCIoBFjU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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