SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c96ba7c5b4ce4cd0d8544333490a358765651a5dade1a5bc25a389715d3d1cce' 
  AND token = 'CdVqGOchOYgsinVeJ15m4izDuVRRcvUCboCzZLgn2cE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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