SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '574ede9e569158289565d6cc947cbe9311e49dfc0beaae1d3d224f7e4589f70c' 
  AND token = 'pIvpK8+ixVFpGK+lDmqKexEm35UmuCoFy4VL4vIJ9+4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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