SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '261a80aa390eeec167cd0c98d349e6b614e7e0a8055135335a3803a8d1597f8d' 
  AND token = 'JhUj2/GUq+XnAo0Q63tAnq0JU+Nk7UYfJtwPPPLXFEM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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