SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0673278e3252af695504c5dadbfe824007660c925f2dc9e32b1c58f17f5da72' 
  AND token = 'bc1SxlAwCDzY6nUZls2P8fi1z4SxdS+fiHMLgXaqfMc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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