SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cde78f1f2ad8b8ce406275fe403786bedeace9cd8bf7882f22c5f98cece66634' 
  AND token = 'GTuRyD3aUglpz+/qOjMY7AYFlJRIMUka09MpBAaVpjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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