SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7d9b6c9d664b33e1514a08ba4c006a9cc8da7dc083ff041023a867f8ac6eebc' 
  AND token = 'pP+xApN6e7nUW/DrOV8w3WfWauqVVs/2YUxjnOhZ4Z4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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