SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2cc5dfdc05c920ac097255785cea6d9f34771091b40f60d3bf5a743f14d5a04' 
  AND token = 'o3AlJyKMOJ2uoesb8KhCvP+evhj/ovrWJIP1xr/gbl8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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