SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '6108d198feebe48b4ce091ec08062fbef81fea5caeaff25191dc05fe5d5fccc7' 
  AND token = 'UDbdEJmijBoEvPs23JZaAtD0sADFtIlM7oLjJWcIra8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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