SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6689a0654afe268cf85242f0d3aedbb808519f6de471fc29120025a42ec6e4d4' 
  AND token = 'uv0sefDF+AfUhZ6rlibkNXSfLzHHeUhqgRJyDnsnlc8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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