SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '273c1a1f9dca0141f0e986dd1d3ebd97f6eac631579669b71340ca0f448b16f7' 
  AND token = 'JZNDEZLOG4fLdkFDX9iLuDkN0lajcF7UoRNWewNhTSI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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