SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91ccfd83ac248f79ae12e33aaa3d57ecf4583229546867f251332c2329fcd928' 
  AND token = 'a/bLPMW3P8+cEOpIPvQL7bi4wvmZQAAGTqadaLs7Pdo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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