SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '52ce255a0840030843d8b1795a46fd3a5d9aab9bb5736e639fe16d598f6fc2ca' 
  AND token = 'xQdHpZm+KZ8cbD0XjgZklhVYaHMpR4hEMMog1aWcj+M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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