SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '849c9320dadcd1a0da8171a8fd05415a72ca5f1db84d6894e2b02d5e5fa49b91' 
  AND token = '2eqNVP1rTK0TDyr5Ij2DnqSCdgC5uVlUHpYP8DZ9kN0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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