SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2f40494045fee6a0a1ef484c6b4eae95db64212dce318a979827fbec6cac82b' 
  AND token = 'jDGOSEihuSFfzvOJYQVvqkbcPQfn296zqmBru1+rUFM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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