SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec2340e2966b4f40174bd4b9b53e16c74c4e3d4efe927926a2696b87f0d0061b' 
  AND token = 'j71FENWT8iS68lyLROSLXkXFbfBogaOwMjuqgFSCllA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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