SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd46568a9d3fc60f811a2488716ad15066a55d2f8407832e590f414d5324d83cf' 
  AND token = '3iiNsxCEbuFDTxSmLsCVF3Hev3cW/YTjY4uzhVrfBKs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}