SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50779f712da211912fda8b110265d041cc7e12bd66fd07452842a7193abdb62d' 
  AND token = 'MxZm/B7+ehF0il0ag/oAQdFkVgZzbSP8ELyaIEZ9Ef4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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