SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3539f0e2a541e8c78de3dd7b97929d32275069e278f61558e94b643c526afe17' 
  AND token = 'awKVqNkgu4Sdf/BRUZB8xY/mh+0FyMsi+wIkNaZoUlM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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